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How to Select Raw Materials for UV 3C Coatings

Release time:

2026-06-18 16:17

How to Select Raw Materials for UV 3C Coatings

The performance of UV‑3C coatings largely hinges on the rational selection of raw materials. From oligomers to reactive diluents, and from photoinitiators to various additives, the choice of each component directly influences key performance attributes such as hardness, adhesion, abrasion resistance, and chemical resistance. Compared with conventional coatings, 3C electronic products impose particularly stringent requirements on coating performance, necessitating meticulous material selection. Understanding the critical considerations for selecting each type of raw material is fundamental to formulation design and product development.

I. Selection of Oligomers

Oligomers are a major constituent in UV‑curable 3C coatings, serving as the film‑forming agent and determining the fundamental properties of the cured coating; therefore, the selection of oligomers is a critical step in formulation design.

When selecting a low‑molecular‑weight oligomer, the first step is to evaluate the performance requirements of the coating. If the coating demands high hardness and excellent wear resistance, a high‑functional‑group polyurethane acrylate is an appropriate choice. Such resins form a highly crosslinked network upon curing, enabling the coating surface to effectively resist scratches and abrasion. For coatings requiring superior flexibility and adhesion, polyether‑based or low‑functional‑group polyurethane oligomers are more suitable; they provide enhanced coating elasticity while ensuring strong bonding between the coating and the substrate. If chemical resistance is required, oligomers bearing specific functional groups should be selected.

Polyurethane acrylates are a widely used class of oligomers in 3C coatings. Their molecular structure contains urethane linkages, which enable the formation of multiple hydrogen bonds between polymer chains, resulting in cured films with excellent wear resistance and flexibility, as well as strong adhesion to substrates such as plastics. Epoxy acrylates represent another important class of oligomers; they exhibit rapid photocuring rates, yielding cured films that are highly rigid, highly glossy, and possess good chemical resistance. In practical formulation design, oligomers with different functionalities and distinct chemistries are often blended to achieve an optimal balance between hardness and flexibility.

In addition, the substrate properties are another critical factor to consider when selecting a oligomer. Plastic substrates impose specific requirements on coating adhesion and chemical resistance; therefore, an oligomer that is compatible with the plastic substrate and provides strong adhesion should be chosen. For commonly used 3C‑industry plastics such as ABS and PC, aliphatic polyurethane acrylates are favored due to their well‑balanced overall performance.

II. Selection of Reactive Diluents

In UV 3C coatings, reactive diluents serve to adjust viscosity while also participating in the photopolymerization reaction and becoming incorporated into the polymer network. They not only dissolve and dilute oligomers to modulate viscosity but also influence the rate of photopolymerization and the various properties of the cured film.

When selecting reactive diluents, multiple factors must be considered. Low toxicity is a fundamental requirement; choose formulations with low odor, low volatility, and minimal irritancy to minimize adverse effects on operators. Low viscosity is a key property of reactive diluents: the lower the viscosity, the greater the diluting power, effectively reducing system viscosity and enhancing coating flow. A neutral color tone is especially critical in clear and white systems to prevent any impact on the coating’s color.

Reactivity is also a critical factor. Reactive diluents with higher reaction rates can accelerate the photocuring process, thereby saving energy and enhancing production efficiency. The functionality of a reactive diluent directly influences the degree of crosslinking: the higher the functionality, the faster the cure, the greater the crosslink density, and the improved hardness and chemical resistance of the coating. In practical formulations, the proportion of each monomer must be carefully balanced, taking into account factors such as coating viscosity, curing speed, and film hardness.

III. Selection of Photoinitiators

Photoinitiators are the key components that enable rapid curing in UV 3C coatings. Under ultraviolet irradiation, photoinitiators absorb light energy and decompose to generate free radicals, which initiate the polymerization reaction. Different types of photoinitiators exhibit distinct absorption characteristics for various UV wavelengths, necessitating selection based on the type of curing light source.

Common types of photoinitiators include free-radical and cationic categories. In 3C coating formulations, the appropriate photoinitiator is typically selected based on the light source type and curing requirements, and multiple photoinitiators are often blended to achieve a balance between surface drying and deep-layer curing.

IV. Selection of Additives

Although additives are used in small quantities in formulations, they significantly influence the coating’s application performance and film quality. Common types of additives include leveling agents and defoamers.

The selection of leveling agents is particularly critical. Leveling agents are used to enhance the spreadability of coatings on substrate surfaces, helping to prevent defects such as pinholes, craters, and orange‑peel texture. Acrylic leveling agents and fluorine‑modified acrylic ester leveling agents can improve coating flatness, while silicone‑based leveling agents are highly effective in enhancing film uniformity and tactile feel; however, they should be used with caution in certain application methods. In electrostatic UV‑curable coating formulations, where the cured film is oriented vertically and exhibits poor flow, it is advisable to minimize or avoid the use of silicone‑based leveling agents.

Defoamers are used to suppress and eliminate air bubbles generated during the mixing, conveying, and spraying of coatings, ensuring that the coated surface is free from pinhole defects. By incorporating various types of additives, formulations can be optimized to meet specific application methods and aesthetic requirements.

V. Conclusion

The selection of raw materials for UV 3C coatings involves multiple aspects, including oligomers, reactive diluents, photoinitiators, and additives. Oligomers, as film-forming agents, determine the coating’s fundamental properties and must be chosen comprehensively based on requirements such as hardness, flexibility, and adhesion. Reactive diluents adjust viscosity and participate in curing; key considerations include low toxicity, low viscosity, and high reactivity. Photoinitiators should be matched to the curing light source, with blending strategies often employed to balance surface drying and deep‑layer curing. Although used in small quantities, additives play a critical role in application performance and surface quality. Appropriately selecting each type of raw material is essential for achieving the desired performance of UV 3C coatings.

Disclaimer: The above content has been compiled from publicly available sources and is provided for reference only. If any infringement occurs, please contact us, and we will address it promptly.

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